Watery Grave [Gatecrash] Rivals of Ixalan Noncreature spells with converted mana

Noncreature spells with converted mana cost equal to the chosen number can't be cast

Set: From the Vault: Realms Type: Land Mythic Cost: {T}: Untap target attacking creature

Set: Conspiracy: Take the Crown Type: Legendary Creature — Goblin Rogue Rare Cost: {R}{R} Whenever a creature you control deals combat damage to a player

but how do we get down

Set: Scars of Mirrodin Type: Artifact — Equipment Mythic Cost: {3} Equipped creature gets +2/+2 and has protection from green and from blue

Watery Grave [Gatecrash] Rivals of Ixalan Noncreature spells with converted manaSet: Gatecrash Type: Land Island Swamp Rare Cost: ({T}: Add {U} or {B}.) As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped. "I fear that as we scurry after phantoms, the Dimir pull nine puppet strings." Ral Zarek